Preheat oven to 350°F (175°C). Grease a 9x5-inch loaf pan and line it with parchment paper. In a large bowl, whisk together the flour, ground pistachios, baking powder, and salt.

In another bowl, rub the orange zest into the sugar with your fingertips until fragrant. Add the eggs, oil, orange juice, and vanilla and whisk until smooth.

Pour the wet mixture into the dry ingredients and fold gently just until combined. Scrape the batter into the prepared pan, smooth the top, and tap the pan on the counter a few times. Bake for 50 to 55 minutes, until a skewer comes out clean. Cool the cake in the pan for 10 minutes, then lift it out and place on a wire rack to cool completely.

Whisk the powdered sugar, honey, and 2 to 3 tablespoons orange juice until you have a thick but pourable glaze. Once the cake is fully cool, pour the glaze over the top and sprinkle with chopped pistachios if you like. Let the glaze set for about 15 minutes before slicing.